Re: [sqlite] C# Dynamic data type

[Adam DeVita]

Interesting idea. Thanks.

Adam

On Tue, Aug 7, 2012 at 12:07 PM, Black, Michael (IS)
 wrote:
> You can use sscanf to determine data type...I've done it before using a 
> method that's not obvious...
>
> You parse from most restrictive to least restrictive format like this...this 
> will accept any valid float format including scientific notation.
>
> #include 
>
> enum {UNKNOWN, FLOAT, INT, STRING};
>
> int datatype(char *s)
> {
>   long i;
>   double f;
>   char buf[4096];
>   int n;
>   n = sscanf(s,"%d%s",,buf);
>   if (n == 1) {
> printf("INT\n");
> return INT;
>   }
>   n = sscanf(s,"%lg%s",,buf);
>   if (n == 1) {
> printf("FLOAT\n");
> return FLOAT;
>   }
>   n = sscanf(s,"%s",buf);
>   if (n == 1) {
> printf("STRING\n");
> return STRING;
>   }
>   else {
>  printf("UNKNOWN\n");
> return UNKNOWN; // should never get here
>   }
> }
>
> main()
> {
>   char *line1="1234";
>   char *line2="1234.5";
>   char *line3="x1234.5";
>   datatype(line1);
>   datatype(line2);
>   datatype(line3);
> }
> ~
>
> Michael D. Black
> Senior Scientist
> Advanced Analytics Directorate
> Advanced GEOINT Solutions Operating Unit
> Northrop Grumman Information Systems
>
> 
> From: sqlite-users-boun...@sqlite.org [sqlite-users-boun...@sqlite.org] on 
> behalf of Adam DeVita [adev...@verifeye.com]
> Sent: Tuesday, August 07, 2012 10:26 AM
> To: General Discussion of SQLite Database
> Subject: EXT :[sqlite] C# Dynamic data type
>
> Good day,
>
> I've been reading a bit of conflicted stuff online in terms of data type.
>
> The most basic question, in  C#, is can you easily determine the data
> type of the Nth entry in a column.
>
> {Ex: Create table A( x TEXT, y )
>  ... a few  inserts, binding a float, then a string, then an int into y..
>
>  select x,y from A
> check the type of y before retrieving a value from it.
> }
>
>
> The docs for  SQLiteDataReader.GetFieldType() seems to read as if it
> will return the column affinity.
>
> regards,
> Adam
> ___
> sqlite-users mailing list
> sqlite-users@sqlite.org
> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
> ___
> sqlite-users mailing list
> sqlite-users@sqlite.org
> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users



-- 
VerifEye Technologies Inc.
905-948-0015x245
151 Whitehall Dr, Unit 2
Markham ON, L3R 9T1
Canada
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] C# Dynamic data type

[Black, Michael (IS)]

You can use sscanf to determine data type...I've done it before using a method 
that's not obvious...

You parse from most restrictive to least restrictive format like this...this 
will accept any valid float format including scientific notation.

#include 

enum {UNKNOWN, FLOAT, INT, STRING};

int datatype(char *s)
{
  long i;
  double f;
  char buf[4096];
  int n;
  n = sscanf(s,"%d%s",,buf);
  if (n == 1) {
printf("INT\n");
return INT;
  }
  n = sscanf(s,"%lg%s",,buf);
  if (n == 1) {
printf("FLOAT\n");
return FLOAT;
  }
  n = sscanf(s,"%s",buf);
  if (n == 1) {
printf("STRING\n");
return STRING;
  }
  else {
 printf("UNKNOWN\n");
return UNKNOWN; // should never get here
  }
}

main()
{
  char *line1="1234";
  char *line2="1234.5";
  char *line3="x1234.5";
  datatype(line1);
  datatype(line2);
  datatype(line3);
}
~  

Michael D. Black
Senior Scientist
Advanced Analytics Directorate
Advanced GEOINT Solutions Operating Unit
Northrop Grumman Information Systems


From: sqlite-users-boun...@sqlite.org [sqlite-users-boun...@sqlite.org] on 
behalf of Adam DeVita [adev...@verifeye.com]
Sent: Tuesday, August 07, 2012 10:26 AM
To: General Discussion of SQLite Database
Subject: EXT :[sqlite] C# Dynamic data type

Good day,

I've been reading a bit of conflicted stuff online in terms of data type.

The most basic question, in  C#, is can you easily determine the data
type of the Nth entry in a column.

{Ex: Create table A( x TEXT, y )
 ... a few  inserts, binding a float, then a string, then an int into y..

 select x,y from A
check the type of y before retrieving a value from it.
}


The docs for  SQLiteDataReader.GetFieldType() seems to read as if it
will return the column affinity.

regards,
Adam
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users